MEMS (Micro Electro Mechanical System) technologies have become quite prevalent in the semiconductor manufacturing industry. MEMS devices, very small mechanical devices driven by electricity, find utility in many applications. MEMS devices often utilize cantilever-type structures that are free to bend and whose movement is detected by electrodes.
There is a drive to form the cantilevers and other MEMS structures to smaller dimensions as is the case for all semiconductor structures. It is desirable to form the cantilevers or other MEMS devices in close proximity to one another and in close proximity to their respective electrodes. In order to achieve this, it is desirable to form openings with high aspect ratios that are not achievable due to the limitations of commercial etchers. In order to form MEMS devices, it is also necessary to “release” the structures such as by etching an underlying oxide layer beneath the cantilever. There are various challenges associated with having an oxide etchant species access and etch the underlying oxide. Current technologies must utilize release holes that extend through the cantilevers or other moveable mechanical structures to provide access to the underlying oxide. These holes adversely impact the mechanical properties of the MEMS device.
It would be desirable to form MEMS and other devices using processes that can etch high aspect ratio openings and underlying oxide materials.